Steerable catheter system having at least one cavity defined in an outer surface thereof and method of using same

ABSTRACT

A steerable catheter system is provided including an elongated shaft having a proximal end, a distal end and an outer surface. The outer surface includes at least one cavity configured to facilitate movement of the distal end relative to the proximal end so as to steer the elongated shaft. A catheter tip is attached to the distal end of the shaft. The catheter tip comprises a curved body having at least one RF cutting edge and at least one non-cutting area recessed from the at least one cutting edge.

The present application is a continuation of U.S. application Ser. No.13/840,010, filed Mar. 15, 2013; (now U.S. Pat. No. 9,216,057); all ofwhich is incorporated by reference herein.

TECHNICAL FIELD

The present disclosure generally relates to medical devices, and moreparticularly to a surgical system and method employing a steerablecatheter device to dissect and evacuate tissue.

BACKGROUND

One of the most common causes of low back pain for the middle-aged andelderly population is lumbar spinal stenosis (LSS), LSS is a medicalcondition in which the spinal canal narrows and compresses the spinalcord and nerves at the level of the lumbar vertebra. Namely, LSSinvolves the narrowing of the lower spinal canal and subsequententrapment of the cauda equina roots by hypertrophy of the osseousand/or soft tissue structures surrounding the lumbar spinal canal. Thisis usually due to the common occurrence of spinal degeneration thatoccurs with aging.

LSS is often associated with incapacitating pain in the back and lowerextremities, difficulty ambulating, leg paresthesias and weakness. Thetypical symptom is increased pain in the legs with walking(pseudoclaudication), which can markedly diminish one's activity level.The characteristic syndrome associated with lumbar stenosis is termedneurogenic intermittent claudication.

There are a number of surgical procedures for the treatment of LSS,including lumbar laminectomy and open decompression surgery. Lumbarlaminectomy is designed to remove a small portion of the bone over thenerve root and/or disc material from under the nerve root to give thenerve root more space. Laminotomy is a microdecompression procedure inwhich a part of the lamina is removed to relieve pressure, or to allowaccess for the surgeon to be able to remove the offending portion of thedisc or the bone spur.

From a surgical perspective, minimally invasive techniques arepreferable when possible. To this end, the use of catheters isdesirable, which can be introduced into body cavities and manipulated tosurgically remove certain tissues. Numerous catheters have been designedto perform various surgical functions. However, many challengers exist,particularly for spinal surgical procedures. For example, it isdifficult to fit and maneuver catheters within the geometry of theinterspinous space and make accurate cuts therein. This couldsignificantly increase the risk of unintentional injury to adjacentareas. This disclosure provides improvements over these prior arttechnologies.

SUMMARY

In one embodiment, in accordance with the principles of the presentdisclosure, a catheter system is provided. The catheter system includesan elongated shaft having a proximal end, a distal end and an outersurface. The outer surface includes at least one cavity configured tofacilitate movement of the distal end relative to the proximal end so asto steer the elongated shaft. A catheter tip is attached to the distalend of the shaft. The catheter tip comprises a curved body having atleast one radio frequency (RF) cutting edge and at least one non-cuttingarea recessed from the at least one cutting edge.

In one embodiment, the catheter system includes an elongated shafthaving a proximal end, a distal end, an inner surface and an outersurface. The outer surface includes at least one cavity configured tofacilitate movement of the distal end relative to the proximal end so asto steer the elongated shaft. The inner surface defines a passageway. Acatheter tip is attached to the distal end of the shaft. The cathetertip comprises a curved body having at least one radio frequency (RF)cutting edge and at least one non-cutting area recessed from the atleast one RF cutting edge. At least one electrode is disposed on thecutting edge configured to emit a cutting radio frequency signal. Aradio frequency generator is operably connected to the catheter tip toprovide radio frequency energy to the at least one electrode. A vacuumis attached to the proximal end of the shaft so as to provide suction toclear cut tissue from the passageway.

In one embodiment, a method of treating a hypertrophied ligamentumflavum in a patient using a steerable catheter device is provided. Themethod includes the steps of: providing a catheter system comprising: anelongated shaft having a proximal end, a distal end, an inner surfaceand an outer surface, wherein the outer surface includes at least onecavity configured to facilitate movement of the distal end relative tothe proximal end so as to steer the elongated shaft, wherein the innersurface defines a passageway, a catheter tip attached to the distal endof the shaft, wherein the catheter tip comprises a curved body having atleast one radio frequency (RF) cutting edge and at least one non-cuttingarea recessed from the at least one RF cutting edge, at least oneelectrode disposed on the at least one cutting edge configured to emit acutting radio frequency signal, a radio frequency generator operablyconnected to the catheter tip to provide radio frequency energy to theat least one electrode, and a vacuum attached to the proximal end of theshaft so as to provide suction to clear cut tissue from the passageway;steering the shaft through tissue such that the catheter tip ispositioned adjacent the hypertrophied ligamentum flavum; and activatingthe radio frequency generator to cut tissue. The catheter design mayalso incorporate a flexible camera to enable direct visualization andhence more accurate cut.

While multiple embodiments are disclosed, still other embodiments of thepresent application will become apparent to those skilled in the artfrom the following detailed description, which is to be read inconnection with the accompanying drawings. As will be apparent, thepresent disclosure is capable of modifications in various obviousaspects, all without departing from the spirit and scope of the presentdisclosure. Accordingly, the detailed description is to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a catheter system in accordance with theprinciples of the present disclosure;

FIG. 2 is a perspective view of the system shown in FIG. 1;

FIG. 3 is an enlarged, perspective view of a component of the systemshown in FIG. 1;

FIG. 4 is an enlarged, perspective view of a component of the systemshown in FIG. 1;

FIG. 5 is an enlarged, perspective view of a component of a cathetersystem in accordance with the principles of the present disclosure;

FIG. 6 is an enlarged, perspective view of a component of a cathetersystem in accordance with the principles of the present disclosure;

FIG. 7 is an enlarged, perspective view of components of the systemshown in FIG. 5;

FIG. 8 is a perspective view of components of the system shown in FIG.5; and

FIG. 9 is a plan view of a spinal segment of a human patient.

Like reference numerals indicate similar parts throughout the figures.

DETAILED DESCRIPTION

The exemplary embodiments of the surgical system and related methods ofuse disclosed are discussed in terms of medical devices for thetreatment of musculoskeletal disorders and more particularly, in termsof a surgical system 100 and method for nerve destruction.

Devices for efficient severing or cutting of a material or substancesuch as nerve and/or soft tissue suitable for use in open surgicaland/or minimally invasive procedures are disclosed. The followingdescription is presented to enable any person skilled in the art to makeand use the present disclosure. Descriptions of specific embodiments andapplications are provided only as examples and various modificationswill be readily apparent to those skilled in the art.

Lumbar spinal stenosis (LSS) may occur from hypertrophied bone orligamentum flavum, or from a lax ligamentum flavum that collapses intothe spinal canal. LSS can present clinical symptoms such as leg pain andreduced function. Conventional treatments include epidural steroidinjections, laminotomy, and laminectomy. Surgical interventions whichremove at least some portion of the lamina are usually performed througha relatively large incision, and may result in spinal instability fromremoval of a large portion of the lamina. Consequently, a percutaneousapproach which removes just enough tissue (lamina or ligamentum flavum)to be effective is provided.

In one embodiment, the catheter is a steerable/deflectable catheter withactive steering or single plane deflection capability. The reach of thecatheter is designed to dissect along the ligamentum flavum. Thecatheter may also have built in irrigation/suction lumens. The tip isdesigned to cut through the ligamentum flavum while protecting the durafrom mechanical or thermal collateral damages. The cutting tip usespulsed radio frequency (RF) to generate a plasma-mediated dischargealong the exposed edge of an insulated tip, creating an effectivecutting edge while minimizing collateral thermal damage. Access throughthe interspinous space with or without distraction allows for bilateralaccess to the ligamentum flavum through one incision and one accesscannula. A flexible camera can be incorporated into the catheter designto allow for direct visualization of space.

It is contemplated that one or all of the components of the surgicalsystem may be disposable, peel-pack, pre-packed sterile devices. One orall of the components of the surgical system may be reusable. Thesurgical system may be configured as a kit with multiple sized andconfigured components, such as, for example, catheters that arepreformed to have different sizes and shapes.

It is envisioned that the present disclosure may be employed to treatspinal disorders, such as, for example, stenosis. It should beunderstood that the present principles are applicable to any spinaldisorder or disorders and defects in other areas of the body. It iscontemplated that the present disclosure may be associated withdiagnostics and therapeutics. It is further contemplated that thedisclosed surgical system and methods may alternatively be employed in asurgical treatment with a patient in a prone or supine position, and/oremploy various surgical approaches, including anterior, posterior,posterior mid-line, direct lateral, postero-lateral, antero-lateral,etc. approaches in the calcaneus, spine or other body regions. Thepresent disclosure may also be alternatively employed with proceduresfor treating the muscles, ligaments, tendons or any other body part. Thesystem and methods of the present disclosure may also be used onanimals, bone models and other non-living substrates, such as, forexample, in training, testing and demonstration.

The present disclosure may be understood more readily by reference tothe following detailed description of the disclosure taken in connectionwith the accompanying drawing figures, which form a part of thisdisclosure. It is to be understood that this disclosure is not limitedto the specific devices, methods, conditions or parameters describedand/or shown herein, and that the terminology used herein is for thepurpose of describing particular embodiments by way of example only andis not intended to be limiting of the claimed disclosure. Also, as usedin the specification and including the appended claims, the singularforms “a,” “an,” and “the” include the plural, and reference to aparticular numerical value includes at least that particular value,unless the context clearly dictates otherwise. Ranges may be expressedherein as from “about” or “approximately” one particular value and/or to“about” or “approximately” another particular value. When such a rangeis expressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. It isalso understood that all spatial references, such as, for example,horizontal, vertical, top, upper, lower, bottom, left and right, are forillustrative purposes only and can be varied within the scope of thedisclosure. For example, the references “upper” and “lower” are relativeand used only in the context to the other, and are not necessarily“superior” and “inferior”.

Further, as used in the specification and including the appended claims,“treating” or “treatment” of a disease or condition refers to performinga procedure that may include administering one or more drugs to apatient (human, normal or otherwise or other mammal), in an effort toalleviate signs or symptoms of the disease or condition. Alleviation canoccur prior to signs or symptoms of the disease or condition appearing,as well as after their appearance. Thus, treating or treatment includespreventing or prevention of disease or undesirable condition (e.g.,preventing the disease from occurring in a patient, who may bepredisposed to the disease but has not yet been diagnosed as having it).In addition, treating or treatment does not require complete alleviationof signs or symptoms, does not require a cure, and specifically includesprocedures that have only a marginal effect on the patient. Treatmentcan include inhibiting the disease, e.g., arresting its development, orrelieving the disease, e.g., causing regression of the disease. Forexample, treatment can include reducing acute or chronic inflammation;alleviating pain and mitigating and inducing re-growth of new ligament,bone and other tissues; as an adjunct in surgery; and/or any repairprocedure. Also, as used in the specification and including the appendedclaims, the term “tissue” includes soft tissue, ligaments, tendons,cartilage and/or bone unless specifically referred to otherwise.

The components of system 100 can be fabricated from biologicallyacceptable materials suitable for medical applications, includingmetals, synthetic polymers, ceramics and bone material and/or theircomposites, depending on the particular application and/or preference ofa medical practitioner. For example, the components of system 100,individually or collectively, can be fabricated from materials such asstainless steel alloys, commercially pure titanium, titanium alloys,Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys,stainless steel alloys, superelastic metallic alloys (e.g., Nitinol,super elasto-plastic metals, such as GUM METAL.® manufactured by ToyotaMaterial Incorporated of Japan), ceramics and composites thereof such ascalcium phosphate (e.g., SKELITE.™ manufactured by Biologix Inc.),thermoplastics such as polyaryletherketone (PAEK) includingpolyetheretherketone (PEEK), polyetherketoneketone (PEKK) andpolyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO.sub.4 polymericrubbers, polyethylene terephthalate (PET), fabric, silicone,polyurethane, silicone-polyurethane copolymers, polymeric rubbers,polyolefin rubbers, hydrogels, semi-rigid and rigid materials,elastomers, rubbers, thermoplastic elastomers, thermoset elastomers,elastomeric composites, rigid polymers including polyphenylene,polyamide, polyimide, polyetherimide, polyethylene, epoxy, bone materialincluding autograft, allograft, xenograft or transgenic cortical and/orcorticocancellous bone, and tissue growth or differentiation factors,partially resorbable materials, such as, for example, composites ofmetals and calcium-based ceramics, composites of PEEK and calcium basedceramics, composites of PEEK with resorbable polymers, totallyresorbable materials, such as, for example, calcium based ceramics suchas calcium phosphate, tri-calcium phosphate (TCP), hydroxyapatite(HA)-TCP, calcium sulfate, or other resorbable polymers such aspolyaetide, polyglycolide, polytyrosine carbonate, polycaroplaetohe andtheir combinations. Various components of system 10 may have materialcomposites, including the above materials, to achieve various desiredcharacteristics such as strength, rigidity, elasticity, compliance,biomechanical performance, durability and radiolucency or imagingpreference.

The components of system 100, individually or collectively, may also befabricated from a heterogeneous material such as a combination of two ormore of the above-described materials. The components of system 100 maybe monolithically formed, integrally connected or include fasteningelements and/or instruments, as described herein.

The following discussion includes a description of a system forperforming a surgical procedure and related methods of employing thesystem in accordance with the principles of the present disclosure.Alternate embodiments are also disclosed. Reference will now be made indetail to the exemplary embodiments of the present disclosure, which areillustrated in the accompanying figures. Turning now to FIGS. 1-9, thereare illustrated components of system 100 in accordance with theprinciples of the present disclosure.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. Thus, for example,reference to “a covering” includes one, two, three or more coverings.

The following discussion includes a description of a system forperforming a surgical procedure and related methods of employing thesystem in accordance with the principles of the present disclosure.Alternate embodiments are also disclosed. Reference will now be made indetail to the exemplary embodiments of the present disclosure, which areillustrated in the accompanying figures. Turning now to FIGS. 1-9, thereare illustrated components of system 100 in accordance with theprinciples of the present disclosure.

System 100 includes an elongated shaft 101 of any shape, size orconfiguration adapted to fit in or at a desired surgical site. Shaft 101includes a proximal end 104, a distal end 106, an inner surface 108 andan outer surface 110. Inner surface 108 defines a passageway 114. Shaft101 has a linear configuration, as shown in FIG. 1. An inner member 111is positioned within passageway 114. Inner member 111 comprises anelastic material, such as, for example, a super elastic metal, such as,for example, Nitinol. Inner member 111 is preformed to have an arcuateconfiguration, as shown in FIG. 2. In some embodiments, inner member 111has a tubular configuration. That is, inner member 111 may include aninner surface that defines a passageway configured for disposal ofinstruments, such as, for example, a suction means and/or an irrigationmeans.

Outer surface 110 includes at least one cavity 112 extendingperpendicular to an axis defined by shaft 101 through inner surface 108and outer surface 110. Shaft 101 may include one or a plurality ofcavities 112. In some embodiments, cavities 112 are provided in a lineararrangement such that cavities 112 are all aligned. In some embodiments,cavities 112 are uniformly spaced apart from one another. In someembodiments, cavities 112 are spaced apart more closely at distal end106 than at proximal end 104. That is, the spacing between cavities 112increases gradually from distal end 106 to proximal end 104, as shown inFIGS. 1 and 2, for example. This configuration allows a greater degreeof bending at proximal end 104 than at distal end 106. It is envisionedthat this configuration may be reversed. That is, the spacing betweencavities 112 can increase gradually from proximal end 104 to distal end106, to allow a greater degree of bending at proximal end 104 than atdistal end 106.

Cavities 112 have a slot-like configuration such that each cavity 112does not extend circumferentially about outer surface 110. That is, eachcavity 112 extends through a first section of outer surface 110 withoutextending through an opposite second section of outer surface 110, thefirst and second sections defining a circumference of outer surface 110.It is envisioned that cavities 112 may be disposed at alternateorientations relative to the axis defined by shaft 101, such as, forexample, transverse and/or other angular orientations such as acute orobtuse and/or may be offset or staggered and/or may be disposed atalternative angular orientations relative to the axis defined by shaft101, depending on the requirements of a particular application.

Cavities 112 are configured to facilitate movement, such as, forexample, bending of distal end 106 relative to proximal end 104 so as toallow a medical practitioner to deflect and steer shaft 101 to a desiredposition after shaft 101 is deployed from a surgical instrument, suchas, for example a cannula. Shaft 101 may be delivered to a surgicalsite, such as, for example, a location adjacent a ligamentum flavum of apatient by delivering shaft 101 through a surgical instrument, such as,for example, a cannula having an inner surface defining a passagewayhaving a uniform diameter along the length of the passageway of thecannula. Inner member 111 is disposed within passageway 114. When shaft101 is disposed within the passageway of the cannula, inner member 111deforms such that inner member 111 and shaft 101 each have a linearconfiguration. When shaft 101 extends through the cannula such thatshaft 101 is spaced apart (positioned outside of) the passageway of thecannula, inner member 111 returns to its arcuate configuration. Becauseinner member 111 is disposed within passageway 114, as inner member 111bends to return to its arcuate configuration, shaft 101 also bends suchthat shaft 101 also assumes an arcuate configuration. The bending ofshaft 101 to impart an arcuate configuration to shaft 101 is facilitatedby cavities 112. Therefore, cavities 112 allow inner member 111 andshaft 101 to move from a first orientation in which inner member 111 andshaft 101 are positioned within a cannula and have a linearconfiguration to a second orientation in which inner member 111 andshaft 101 are positioned outside a cannula and have an arcuateconfiguration. The amount of curvature of shaft 101 when shaft 101 is inthe second orientation may be altered by modifying the number andlocation of cavities 112 to achieve the desired amount of curvature,according to the preference of a medical practitioner.

Shaft 101 may comprise a flexible, long, hollow tube which is capable ofoptionally passing materials such as guide wires, control wires, drugs,sensors, sensor fibers or wires, power, suction tubes, irrigation tubes,ultrasonic signals, drive shafts, etc. Materials such as guide wires,control wires, drugs, sensors, sensor fibers or wires, power, suctiontubes, irrigation tubes, ultrasonic signals, drive shafts, etc. may alsobe passed through the passageway defined by the inner surface of innermember 111 when inner member 111 is positioned within passageway 114. Itis envisioned that all or only a portion of shaft 101, cavities 112and/or passageway 114 may have alternate cross section configurations,such as, for example, circular, oval, oblong, triangular, square,rectangular, polygonal, irregular, uniform, non-uniform, offset,staggered, undulating, arcuate, variable and/or tapered, according tothe requirements of a particular application.

Distal end 106 of the shaft 101 includes at least one catheter tip 103.In some embodiments, catheter tip 103 includes a cylindrical distalportion 117 disposed in passageway 114 such that an outer surface ofdistal portion 117 engages inner surface 108 of shaft 101 to fixcatheter tip 103 to shaft 101. It is envisioned that the outer surfaceof distal portion 117 and inner surface 108 of shaft 101 may each bethreaded such that the threads on the outer surface of distal portion117 engage the threads on inner surface 108 of shaft 101 to fix cathetertip 103 with shaft 101. It is further envisioned that distal portion 117of catheter tip 103 may be disposed with shaft 101 in alternate fixationconfigurations, such as, for example, friction fit, pressure fit,locking protrusion/recess, locking keyway and/or adhesive. In someembodiments, a proximal end surface of distal portion 111 engages adistal end surface of shaft 101 to fix catheter tip 103 with shaft 101.In some embodiments, shaft 101 and catheter tip 103 are integrallyformed or monolithic.

Catheter tip 103 includes at least one electrode to provide catheter tip103 with at least one cutting edge, such as, for example, a radiofrequency (RF) emitting edge. It is envisioned that catheter tip 103 mayinclude one or a plurality of cutting edges. In some embodiments, system100 includes a radio frequency (RF) generator 102 that delivers RFenergy to the RF emitting cutting edge(s) and includes a power source(not shown). It is envisioned that generator 102 may be configured todeliver monopolar RF energy and/or bipolar RF energy or pulsed plasma RFenergy.

In some embodiments, shaft 101 may be configured to deflect in a singleplane. This can be achieved by arranging cavities 112 in a lineararrangement on only one side of shaft 101, as shown in FIG. 1.Configuring shaft 101 to deflect in a single plane can also be achievedby providing shaft 101 with a non-round configuration such as aflattened, oblong shape having, e.g., a substantially rectangularcross-section (e.g., as shown in FIG. 7). This enables the shaft 101 tobe positioned and moved to achieve various angles and curves which aresubstantially co-planar. For example, FIG. 2 depicts a side view ofsystem 100 with shaft 101 in a deflected position (in the secondorientation). It is envisioned that shaft 101 may be configured todeflect through multiple planes by providing a first series of cavities112 arranged in a linear configuration on one side of shaft 101 and asecond series of cavities 112 arranged in a linear configuration on anopposite side of shaft 101, the sides of shaft 101 defining thecircumference of shaft 101. Inner member 111 is positioned withinpassageway 114 such that shaft 101 deflects through a first plane whenshaft 101 is in the second orientation. Inner member 111 may be then berotated 180 degrees within passageway 114 such that shaft 101 deflectsthrough a second plane when shaft 101 is in the second orientation, thesecond plane being different than the first plane.

In some embodiments, catheter tips are provided which are designed toeffectively cut through the ligamentum flavum while protecting tissuessuch as the dura against mechanical and/or thermal collateral damage,and which can access the interspinous space with or without distractionto allow for bilateral access to the ligamentum flavum through oneincision and one access cannula (shaft 101). These objectives can beachieved through various configurations, as depicted and describedherein.

FIG. 3 depicts an enlarged perspective view of catheter tip 103.Catheter tip 103 is in communication with passageway 114 such that cuttissue can be directed proximally from catheter tip 103 into passageway114 for removal from a surgical site. In some embodiments, catheter tip103 comprises a curved body 303 having two ends 305 defining a C-shapedrecess 309. Body 303 may include a first area (a cutting area)configured for cutting e.g., tissue/bone, and a second area configuredto be a non-cutting area, which may comprise, e.g., an insulatingmaterial, such as, for example, thermal plastic, to protect tissue/bonefrom mechanical or thermal damage or cutting action. Ends 305 areconfigured to prevent damage to adjacent tissue and/or nerves duringdissection of the ligamentum flavum.

In some embodiments, the first area comprises a cutting edge in the formof a cutting wire 301 which may be affixed to each of the two ends 305,e.g., by being inserted into apertures 307 therein. Any alternate meansfor attaching cutting wire 301 to catheter tip 103 may be contemplated.Any of the cutting areas/edges described herein, including cutting wire301, may comprise of any material which can effectively use RF energy togenerate a plasma-mediated discharge and thus form an effective cuttingedge, such as for example, platinum or platinum-iridium alloys, etc.

FIG. 4 is an enlarged perspective view of catheter tip 103. Body 303includes at least one second (non-cutting) area 311 having an arcuateshape which is opposite from and recessed with respect to the straightcutting wire 301. It is envisioned that body 303 and/or area 311 may bevariously configured and dimensioned, such as, for example, planar,linear, arcuate, concave, convex, polygonal, irregular, uniform,non-uniform, staggered, tapered, consistent or variable, depending onthe requirements of a particular application.

Further configurations of catheter tips are provided. For example, FIG.5 is an enlarged perspective view of a catheter tip 501. Catheter tip501 comprises a hollow oblong housing 502 having a recess 507. Housing502 may be configured to be attached to a distal end of the shaft 101having an oblong flattened shape such as that which is shown in FIG. 7.It is envisioned that all or only a portion of housing 502 may bevariously configured and dimensioned, such as, for example, circular,oval, oblong, triangular, square, rectangular, polygonal, or irregular,depending on the requirements of a particular application.

Catheter tip 501 includes at least two opposing raised non-cutting areas505 which are positioned along the elongated (i.e., longer) sides ofhousing 502. Catheter tip 501 includes at least two opposing recessedcutting edges 503 which are situated on the shorter ends of the housing502 and which adjoin the raised non-cutting areas 505. In variousembodiments, the non-cutting edges 505 protrude beyond the cutting edges503.

FIG. 6 is an enlarged perspective view of a catheter tip 601. Cathetertip 601 comprises a hollow cylindrical body 602 defining a cavity 607. Adistal end of body 602 includes a protruding tip 609 shaped as ahalf-circle which extends from a portion of body 602. Tip 609 includes aplurality of cutting edges 603 which protrude from body 602. Forexample, cutting edges 603 may comprise one U-shaped edge which connectstwo straight edges that extend from body 602 in an axial direction. Thebody 602 includes a non-cutting edge 605 which is recessed from thecutting edges 603. The non-cutting edge 605 may comprise, e.g., aU-shaped edge. It is envisioned that all or only a portion of body 602,tip 609 and/or edges 603 may be variously configured and dimensioned,such as, for example, circular, oval, oblong, triangular, square,rectangular, polygonal, or irregular, depending on the requirements of aparticular application.

Any alternate configurations of catheter tips may be contemplated whichinclude cutting areas and non-cutting areas oriented in various planes,positions and locations on the catheter tip, and having various shapesand sizes.

FIG. 7 is an enlarged perspective view of catheter tip 501 attached to adistal end 707 of shaft 101. In various embodiments, shaft 101 mayinclude one or more apertures of any desired shape or size to provideadditional operational features. For example, shaft 101 may include anaperture 701 for irrigation capability, an aperture 703 for power, andan aperture 705 for suction capability. Additional features or aperturesmay be provided in shaft 101 which are capable of optionally passingmaterials such as guide wires, control wires, drugs, sensors, sensorfibers or wires, power, suction tubes, irrigation tubes, ultrasonicsignals, drive shafts, etc.

In some embodiments, shaft 101 may be co-extruded with at least twodifferent types of materials having different properties (differentdensities, hardness, flexibility, etc.). FIG. 8 is a perspective view ofa co-extrusion shaft 801 in accordance with the principles of thepresent disclosure. Shaft 801 comprises a hollow cylindrical tubecomprised of different materials, for example at least two differentmaterials. In some embodiments, shaft 801 comprises at least twodifferent materials which are co-extruded in a staggered configuration.For example, a first material 803 may be provided on opposing sides ofshaft 801 which each adjoin a second material 805 also on opposing sidesof shaft 801, as shown in FIG. 8. It is envisioned that the differentcharacteristics and/or properties of the co-extruded materials 803, 805may impart a desired range of motion, resiliency, flexibility, etc. toshaft 801. For example, shaft 801, while provided in a shape having around cross-section, may be caused to deflect in a single plane (or anyother predetermined direction) due to the selected hardness propertiesof each of the first and second materials 803, 805.

FIG. 9 is a plan view of an exemplary spinal segment 900 showing theorientation of various ligaments, tissues and voids, such as aninterspinous space 901 (which can provide an access point for thecatheter device), a ligamentum flavum 911, an interspinous ligament 913,a supraspinous ligament 915, spinal dura 909, a posterior longitudinalligament 907, a venous plexus 905, and epidural fat 903. In someembodiments, the components of system 100 may be shaped or formed to fitin the interspinous space.

The components of system 100 may be sterilizable. In variousembodiments, one or more components of system 100 are sterilized byradiation in a terminal sterilization step in the final packaging.Terminal sterilization of a product provides greater assurance ofsterility than from processes such as an aseptic process, which requireindividual product components to be sterilized separately and the finalpackage assembled in a sterile environment.

In some embodiments, gamma radiation is used in the terminalsterilization step, which involves utilizing ionizing energy from gammarays that penetrates deeply in the device and/or covering. Gamma raysare highly effective in killing microorganisms. Gamma rays can beemployed when the device is in the package and gamma sterilization doesnot require high pressures or vacuum conditions, thus, package seals andother components are not stressed. In addition, gamma radiationeliminates the need for permeable packaging materials.

In various embodiments, electron beam (e-beam) radiation may be used tosterilize one or more components of system 100. E-beam radiationcomprises a form of ionizing energy, which is generally characterized bylow penetration and high-dose rates. E-beam irradiation is similar togamma processing in that it alters various chemical and molecular bondson contact, including the reproductive cells of microorganisms. Beamsproduced for e-beam sterilization are concentrated, highly-chargedstreams of electrons generated by the acceleration and conversion ofelectricity. E-beam sterilization may be used, for example, when thecatheter device and/or system is included in a gel. Other methods mayalso be used to sterilize one or more components of system 100 includinggas sterilization, such as, for example, with ethylene oxide or steamsterilization.

In various embodiments, the catheter tip can be equipped with a camerafor viewing tissue as the catheter is used in situ. The camera can beinterconnected with a low power radio frequency transmitter so as totransmit images recorded by the camera to a display module in theoperating room. Transmitters of this type are commercially available andcan be adapted for the intended use. The image captured by the cameracan be digitized and recorded by a camera. The image recorded by thecamera can also be displayed real time on a video monitor through thewireless interconnection. The ease of a wireless transmission system inthe confines of an operatory avoids the likelihood of a patient andattending health care providers from becoming entangled with cords andwires. In one embodiment, the camera can be located at the distal end ofthe catheter tip and a light source is provided so as to provide betterimages transmitted from the camera. In one embodiment the light sourcecomprises at least one diode strategically placed on the catheter inorder to provide amble but focused light on the area to be imaged by thecamera.

A method for treating a surgical site is provided in accordance with thepresent disclosure which includes providing a catheter comprising ashaft shaped to fit into a desired surgical site, e.g., between twoadjacent spinous processes. System 100 may be used in any suitableapplication. In some embodiments, system 100 may be used in treatment oflumbar spinal stenosis, vertebral compression fractures, interbodyfusion, minimally invasive procedures, posterolateral fusion, correctionof adult or pediatric scoliosis, treating long bone defects,osteochondral defects, ridge augmentation (dental/craniomaxillofacial,e.g. edentulous patients), beneath trauma plates, tibial plateaudefects, filling bone cysts, wound healing around trauma, contouring(cosmetic/plastic/reconstructive surgery), and others. System 100 may beused in a minimally invasive procedure via placement through a smallincision, via delivery through a tube, cannula or other access device.The size and shape may be designed with restrictions on deliveryconditions.

In assembly, operation and use, system 100 is employed with a surgicalprocedure, such as, for a treatment of a hypertrophied ligamentumflavum. It is contemplated that one or all of the components of system100 can be delivered or implanted as a pre-assembled device or can beassembled in situ. System 100 may be completely or partially revised,removed or replaced.

In use, to treat a hypertrophied ligamentum flavum, the medicalpractitioner obtains access to a surgical site including in anyappropriate manner, such as through the skin, or through an incision andretraction of tissues. In one embodiment, a drill is employed to removebone tissue to provide access to a repair site. It is envisioned thatsystem 100 can be used in any existing surgical method or techniqueincluding open surgery, mini-open surgery, minimally invasive surgeryand percutaneous surgical implantation, whereby the fractured or injuredbone is accessed through a mini-incision or sleeve that provides aprotected passageway to the area. Once access to the surgical site isobtained, the particular surgical procedure can be performed fortreating the injury or disorder. The configuration and dimension ofsystem 100 is determined according to the configuration, dimension andlocation of a selected section of nerves and the requirements of aparticular application.

An incision is made in the body of a patient and a cutting instrument(not shown) creates a surgical pathway for implantation of components ofsystem 100. Shaft 101 is inserted into a surgical site 900 and ismanipulated and steered such that tip 103 is deployed to a positionadjacent ligamentum flavum 911. Cutting wire 301 is activated to dissecttissue as shaft 101 moves along ligamentum flavum 911. Ends 305 areshaped to protect adjacent tissue from being damaged during cutting. Anirrigation or vacuum to supply suction can be attached to system 100such that cut tissue can be removed from passageway 114 within shaft101. In some embodiments, the shaft is flexible in at least a singleplane to facilitate manipulation and positioning of the catheter devicewithin the surgical site. In other applications, the catheter system maybe applied to transverse processes or spinous processes of vertebrae.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplification of thevarious embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.The embodiments above can also be modified so that some features of oneembodiment are used with the features of another embodiment. One skilledin the art may find variations of these preferred embodiments, which,nevertheless, fall within the spirit of the present invention, whosescope is defined by the claims set forth below.

Although the invention has been described with reference to preferredembodiments, persons skilled in the art will recognize that changes maybe made in form and detail without departing from the spirit and scopeof the invention.

We claim:
 1. A catheter system for operating on tissue at a surgicalsite in a patient, the catheter system comprising: an elongated shaftdefining an axis, the shaft having a proximal end, a distal end, and anouter surface, the outer surface defining a circumference, and includingat least one non-circumferential cavity extending through at least aportion of the outer surface, the at least one cavity being configuredto define a bending movement of the distal end relative to the proximalend; and a catheter tip attached to the distal end of the shaft, thecatheter tip comprising a curved body having at least one cutting edge,and at least one non-cutting area recessed from the at least one cuttingedge; wherein the bending movement of the distal end relative to theproximal end defined by the at least one cavity is adapted to facilitatedeflection and steering of the shaft through the patient to the surgicalsite.
 2. The catheter system of claim 1, wherein the shaft isdeflectable in a single plane.
 3. The catheter system of claim 1,wherein the at least one cutting edge comprises at least one RF cuttingedge, the at least one RF cutting edge including at least one electrodeconfigured to emit a cutting radio frequency signal and the at least onenon-cutting area, the at least one non-cutting area being insulated,thereby substantially localizing the radio frequency signal at the atleast one RF cutting edge.
 4. The catheter system of claim 3, furthercomprising a radio frequency generator operably connected to thecatheter tip to provide radio frequency energy to the at least oneelectrode.
 5. The catheter system of claim 1, wherein the at least onecutting edge comprises a cutting wire attached to two opposing tipsextending from the curved body.
 6. The catheter system of claim 3,wherein the catheter tip comprises a hollow oblong housing having arecess, said at least one non-cutting area comprises at least twoopposing raised non-cutting edges having a first height, and said atleast one RF edge comprises at least two opposing recessed cutting edgeshaving a second height.
 7. The catheter system of claim 1, furthercomprising a camera configured for imaging the tissue.
 8. The cathetersystem of claim 6, wherein the first height is greater than the secondheight.
 9. The catheter system of claim 1, wherein the catheter tipcomprises a hollow substantially cylindrical body having a cavity andincluding a protruding tip shaped as a substantial half-circle whichextends from a portion of the substantially cylindrical body, theprotruding tip including the at least one cutting edge, the at least onecutting edge comprising a plurality of cutting edges, wherein the bodyincludes the at least one non-cutting area, the at least one non-cuttingarea being recessed from the plurality of cutting edges.
 10. Thecatheter system of claim 9, wherein the plurality of cutting edgesdefine a substantially U-shaped cutting edge which connects two straightedges that extend from the substantially hollow cylindrical body in theaxial direction, an upper-open portion of the substantially U-shapedcutting edge being oriented toward the distal end of the shaft.
 11. Thecatheter system of claim 9, wherein the recessed non-cutting areacomprises a substantially U-shaped non-cutting edge, an upper-openportion of the substantially U-shaped cutting edge being oriented towardthe distal end of the shaft.
 12. The catheter system of claim 1, whereinthe shaft is comprised of at least two co-extruded materials, each ofthe at least two co-extruded materials having different materialproperties.
 13. A steerable catheter system for operating on tissue at asurgical site in a patient, the steerable catheter system comprising: anelongated shaft defining an axis, the shaft having a proximal end, adistal end, an inner surface, the inner surface defining a passageway,and an outer surface, the outer surface defining a circumference andincluding at least one non-circumferential cavity extending through atleast a portion of the outer surface, the at least one cavity beingconfigured to define a bending movement of the distal end relative tothe proximal end; a catheter tip attached to the distal end of theshaft, wherein the catheter tip comprises a curved body having at leastone radio frequency (RF) cutting edge and at least one non-cutting arearecessed from the at least one RF cutting edge; at least one electrodedisposed on the at least one RF cutting edge and configured to emit acutting radio frequency signal; a radio frequency generator operablyconnected to the catheter tip to provide radio frequency energy to theat least one electrode; and a vacuum configured for attachment to theproximal end of the shaft so as to provide suction to clear cut tissuefrom the passageway; wherein the bending movement of the distal endrelative to the proximal end defined by the at least one cavity isadapted to facilitate deflection and steering of the shaft through thepatient to the surgical site.
 14. The catheter system of claim 13,wherein the at least one non-cutting area is arcuate and recessed fromthe at least one RF cutting edge.
 15. The catheter system of claim 13,wherein the catheter tip comprises a hollow oblong housing having arecess, said housing including the at least one non-cutting area and theat least one RF cutting edge, the at least one non-cutting edgecomprising at least two opposing raised non-cutting areas and the atleast one RF cutting edge comprising at least two opposing recessedcutting edges, wherein the at least two raised non-cutting areas arepositioned on opposing sides of the oblong housing having a firstheight, and wherein the at least two recessed cutting edges arepositioned on opposing sides of the oblong housing having a secondheight, the first height being greater than the second height, the atleast two raised non-cutting areas being located.
 16. The cathetersystem of claim 13, wherein the catheter tip comprises a hollowsubstantially cylindrical body having a cavity and including aprotruding tip shaped as a substantial half-circle which extends from aportion of the substantially cylindrical body, the protruding tipincluding the at least one RF cutting edge, the at least one RF cuttingedge comprising a plurality of cutting edges, wherein the body includesthe at least one non-cutting area, the at least one non-cutting areabeing recessed from the cutting edges.
 17. The catheter system of claim13, further comprising a camera configured for imaging tissue.
 18. Amethod of treating a hypertrophied ligamentum flavum at a surgical sitein a patient, the method comprising: utilizing a catheter system, thecatheter system comprising: an elongated shaft defining an axis, theshaft having a proximal end, a distal end, an inner surface, the innersurface defining a passageway, and an outer surface, the outer surfacedefining a circumference and including at least one non-circumferentialcavity extending through at least a portion of the outer surface, the atleast one cavity being configured to define a bending movement of thedistal end relative to the proximal end, a catheter tip attached to thedistal end of the shaft, wherein the catheter tip comprises a curvedbody having at least one radio frequency (RF) cutting edge and at leastone non-cutting area recessed from the at least one cutting edge, atleast one electrode disposed on the at least one RF cutting edge andconfigured to emit a cutting radio frequency signal, a radio frequencygenerator operably connected to the catheter tip to provide radiofrequency energy to the at least one electrode, and a vacuum attached tothe proximal end of the shaft so as to provide suction to clear cuttissue from the passageway, wherein the bending movement of the distalend relative to the proximal end defined by the at least one cavity isadapted to facilitate deflection and steering of the shaft through thepatient to the surgical site, utilizing the bending movement defined bythe at least one cavity on the outer surface of the shaft to steer theshaft through the patient; positioning the catheter tip adjacent thehypertrophied ligamentum flavum; activating the radio frequencygenerator; and cutting tissue from the hypertrophied ligamentum flavumwith the at least one RF cutting edge.
 19. The method of claim 18,wherein the catheter tip comprises a hollow oblong housing having arecess, said housing including the at least one non-cutting area and theat least one RF cutting edge, the at least one non-cutting areacomprising at least two opposing raised non-cutting edges having a firstheight, and the at least one RF cutting edge comprising at least twoopposing recessed cutting edges, the at least two recessed cutting edgesbeing positioned on opposing sides of the oblong housing having a secondheight, the first height being greater than the second height.
 20. Themethod of claim 18, wherein the catheter tip comprises a hollowsubstantially cylindrical body having a cavity and including aprotruding tip shaped as a substantial half-circle which extends from aportion of the substantially cylindrical body, the protruding tipincluding the at least one cutting edge, the at least one cutting edgecomprising a plurality of cutting edges, wherein the body includes thenon-cutting area which is recessed from the cutting edges.
 21. Thecatheter system of claim 1, wherein the at least one non-circumferentialcavity comprises a plurality of non-circumferential cavities defined atspaced intervals on the outer surface, each of the plurality ofnon-circumferential cavities being substantially perpendicular to theaxis.
 22. The catheter system of claim 21, wherein the spaced intervalsof a first plurality of the plurality of recesses proximate the distalend of the elongated shaft are less than the spaced intervals of asecond plurality of the spaced intervals proximate the proximal end ofthe elongated shaft.